Telephone-transmitter.



No. 791,892. PATENTED JUNE 6, 1905. M. J. FLETCHER.

TELEPHONE TRANSMITTER.

APPLICATION FILED MAB. 3, 1904.

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Mean/ Patented June 6, 1905.

PATENT OFFICE.

MILTON J. FLETCHER, OF SAN ANTONIO, TEXAS.

TELEPHONE-TRANSMITTER.

SPECIFICATION forming part of Letters Patent No. 791,892, dated June 6,1905.

Application filed March 3, 1904. Serial No. 196,338.

To all 2071,0772, it flea/y concern.-

Be it known that I, MILTON J. FLETCHER, a citizen of the United States,residing at San Antonio, in the county of Bexar and State of Texas, haveinvented new and useful Improvements in T elephone-Transmitters, ofwhich the following is a specification.

This invention relates to improvements in that class oftelephone-transmitters known as variable-contact transmitters; and theobjects thereof are the provision of means for the ready detachment andassemblage of its parts with the least possible chance of injurythereto, simplicity of construction and expedition in the adjustment ofthe parts, and to vary the granular resistance and reduce to a minimumthe displacement of the carbon granules, which in transmitters of thisclass often causes a partial, if not complete, failure of the instrumentto perform its function.

With these and other objects and advantages in view the inventionconsists in the construction and arrangement of the parts, which will bemore fully hereinafter set forth.

In the drawings, Figure 1 is a longitudinal vertical section of atransmitter embodying the features of the invention. Fig. 2 is a planview of the diaphragm. Fig. 3 is a detail longitudinal section of aportion of the transmitter. Fig. 4: is a detail plan view of a portionof one of the diaphragm-holding springs. Fig. 5 is a detail plan view ofone of the cam bolts used in connection with the diaphragmsprings. Fig.6 is a detail view showing parts of the improved transmitter inseparated position.

Similar numerals of reference are employed to indicate correspondingparts in the several views.

It is generally assumed that a telephonetransmitter seldom gets out oforder; but if treated roughly, as is often the case, with portabletelephones especially, it frequently becomes disabled and ordinaryadjustment will not suflice to restore it to working order. Then itbecomes necessary to open a transmitter, it should be so constructedthat it may be quickly and conveniently opened by a person who may notbe familiar with its working parts with the least possible chance ofinjury. If too many screw-heads or nuts be in sight or if the diaphragmbe in any Way connected to the front electrode, the wrong fastenings areapt to be removed first or the delicate parts injured by removal of thediaphragm. With these disadvantages in view and after considerableexperience with split granules in some and torn mica in othertransmitters the present form of transmitter has been devised toovercome tendency to injury thereto under the conditions just set forth.

In the present construction the case is preferably of metal and consistsof a front circular Wall 1, having an integral front plate 2 with acentral screw-threaded orifice 3 to removably receive the inner reducedextremity of a hard-rubber mouthpiece 4:. which may be provided with theusual apertured or grated occluder. The wall 1 rests against a-shoulderformed by a flange 5, surrounding the periphery of a back plate 6, whichhas at its center a rearwardly-projecting cavity 7 provided with a rearcylindrical extension 8 for connection to a tubular supporting-arm 9.The back plate is held firmly against the wall 1 by bolts 10, havingscrew-threaded extremi ties projecting through said back plate toreceive readily-removable nuts 11. The extremi ties of the bolts 11within the body of the transmitter are enlarged to form cam-heads 12,having near their inner terminals openings 13, one in each head, asclearly shown by Fig. 5, and extending through the said openings arefulcrum-screws or analogous fastenings 14:. When the bolts 10 aredisposed as shown by Fig. 1, the parts of the case will be held in firmassembled condition and the camheads of the bolts perform anotherfunction, which will now be described. Aring 15, of blotting-paper orother suitable resilient material, is arranged against the inner rearside springs has oppositely-extending arms and a centralangularly-disposed connecting member 18, with a slot 19 opening outthrough one side. The slots of the connecting members 18 are caused toengage the fulcrumscrews let, and said connecting members are interposedbetween the heads 12 of the bolts 10 and the inner surface of the wall1, as shown by Fig. 1. When the bolts 10 are arranged as shown by Fig.1, theheads 12 thereof press against the springs 17 and force thediaphragm 16 closely and firmly into engaging relation to the ring 15.If it is desired at any time to remove the diaphragm, an operatorunderstanding the arrangement of the parts will remove the bolts 10inwardly to cause the cam-heads 12 thereof to become disengaged from thesprings 17 and relieve the diaphragm of securing pressure, and the saiddiaphragm may be removed by disengaging the connecting members 18 of thesprings from the fulcrum-screws 1 1. If the parts of the case areseparated by one not understanding the construction and mode ofseparating and assembling the springs or the cam function of the bolts,injury to or irregular adjustment of the diaphragm will be prevented.The heads of the fulcrum-screws 1 1 are located on the interior of theease, and this disposition prevents said screws from being molested byan attempt to open the case from the exterior, the nuts 11 being theonly exteriorly-accessible fastenings.

The diaphragm 16 is formed from any desirable material applicable forthe purpose, and projecting rearwardly from the center thereof is a bossor lug 17, having a finelyscrew-threaded opening 18 in the centerthereof to receive a small thumb adjusting-screw 19, provided with alock or jam nut 20. This adjusting-screw 19* is disposed in operativerelation to a cap 21., governing a front electrode 22 to bring thelatter under the influence of the vibrations of the diaphragm. Theelectrode 22 is supported in a cup 23, secured in the cavity 7, the cupbeing formed with a central rearwardly-projecting stem 24:, extendingthrough a central opening in the rear wall of the cavity and engaged bya cap-nut 25. Between the stem 21 and the wall of the opening in therear side of the cavity 7 is an angularlyshaped insulatingsleeve 26, thefront end of the cap-nut 25 closely impinging against the said sleeveand forcing it to its place. The electrode 22 is formed from carbon andthe cap 21 of metal, and between the cap and the electrode is a micadisk 27, which is held firmly on the cup 23 by a ring 28. The diameterof the electrode 22 is considerably less than the inner diameter of thecup, and the metal cap 21 is held in connected relation thereto by acenter screw 29, having its head countersunk in the rear side of theelectrode. Against the back of the cup 23 is a stationary electrode 30,which is held in place by a screw 31, having its head countersunk in thefront face of said electrode and its shank ejected into the stem 24. Theelectrode 22 is free to vibrate, and between the two electrodes in thechamber of the cup 23 a granular carbon 31 is disposed, the said cupbeing lined with suitable paper. The electrode 22 and mica disk carryingthe same are made readily removable from the cup, and the electrode 30is replaceable by other electrodes differing in 32 of U-shaped form,which embraces andbears against the cap-nut 25, said spring being heldin connection with the disk by a screw or analogous fastening 33, towhich is also fastened the usual flexible insulated conductor 34. Fig. 3shows a modification of the structure just explained and consists indisposing the disk 31 against a shoulder 35, formed in the tubular arm 9and held in place by the rear end of the cylindrical extension 8 of thecavity 7, the disk 31 in this arrangement carrying the same parts asheretofore described. The cylindrical extension 8 in the modifiedconstruction shown by Fig. 3 is circumferentially grooved, as at 36, andis held in place by set-screws 37 engaging said groove, three of thesescrews being used, but only one shown in the drawings. It will beunderstood that the adjusting-screw 19 is brought into contact with thecap 21, and as this screw is exteriorly accessible after the mouthpiece4: is removed adjustment thereof may be readily eifected to vary thepressure of the end of the screw on the cap to affect the diaphragm, aswill be readily understood. This working electrode 22 is governed by thevibratile action of the diaphragm upon the cap or disk 21, and thediameter of said cap or disk is slightly less than the electrode 22 tocause the mica disk 27 to have more flexibility. Between this mica disk27 and the electrode 22 a circular piece of silk of the same diameter asthe electrode is interposed, as at 38, the outer edge of said silk beingpreferably fringed to prevent the granules of carbon entering betweenthe same and the mica disk or washer. Mica will adapt itself better tothe surface of the silk than it would to the carbon of which theelectrode 22 is composed, and, further more, the use of mica inconstructing the disk or washer 27 is preferable, as it is moresusceptible to the vibratile action of the diaphragm and the delicateadjustment. The mica disk or washer, however, will be thicker than thatusually employed consistent with the best results. The cap or disk 21,mica disk 27, silk piece 38, and, the carbon electrode 22 are firmlybound together by the center screw 29, arranged as heretofore set forth.By having the electrode 22 slightly less in diameter than the innerdiameter of the cup 23 a space of sufficient width between the peripheryof the electrode and the cup is provided to prevent the carbon granulesfrom binding.

In a transmitter constructed in accordance with the foregoingdescription the electrical current passes from one side of the line orbattery through the supporting-arm 9 to the case or shell, and in thelatter the current divides, equal portions passing through thedamping-springs to the diaphragm, thence to the adj Listing-screw 19,and from the latter to the screw 29, carbon disk 22, granulated carbon31, stationary electrode or carbon disk 30, and from the latter to theusual insulated conductor 34 in the supporting-arm 9, which conductssaid current to the other side of the battery or line. Thedamping-springs, case, diaphragm, adjusting-screw 19, and cap or disk 21all being of metal, it will readily be seen that where one of theseparts comes in contact with the other an electrical contact is formedwhich permits the passage of the current of one of said parts to theother. The use of the adjusting-screw 19 and cap or disk 21 in therelation set forth obviates the necessity of the usual flexibleconductor leading from the cap to some point on the case.

In view of the foregoing construction the transmitter if roughlyhandled, as usual in portable telephones, the working elements will bepreserved in operative relation and will not become deranged or damagedno matter how rough the treatment thereof may be, and when it becomesnecessary to examine the elements the latter will be protected if oneperforming the examination be unfamiliar with telephone construction.

The several metallic parts on the transmitter will be provided withinsulating sheets, washers, or other analogous devices commonly used inthe art, and the cup 23 has its rear wall or terminal insulated from thecavity 7 by a sheet or washer 38, of suitable insulating material.

Having thus fully described the invention, what is claimed as new is 1.A telephone-transmitter, having a cup carrying a fixed and a movableelectrode, the two electrodes being held in spaced relation, an integralstem on said cup, a cap on said stem, a spring contacting with said cap,a granular resistance substance interposed between the two electrodes, adiaphragm having an adjustable device cooperating with the movableelectrode, and electrical connections.

2. In a telephone-transmitter, the combination of acasing, a tubularsupport for the easing, a cup disposed in the casing and having arearwardly-projecting stem, electrodes.

mounted in the cup and held spaced apart from each other, one of theelectrodes being vibratile, a granular resistance substance interposedbetween the electrodes, a metallic cap on the rear terminal of the stem,an insulating-disk in the tubular support having a contact-spring toengage said cap, a metallic contact carried by the vibratile electrode,a diaphragm having an adjusting-screw extending therethrough tocooperate with said contact on the vibratile electrode, and electricalconnections.

3. In a telephone-transmitter, the combination of a casing, a diaphragmdisposed in the casing, electrodes in operative relation to thediaphragm, and fastening means pivotally mounted within the casing andhaving enlarged extremities to exert a securing pres sure against thediaphragm and screw-threaded portions projected through the casing andexteriorly accessible.

4. In a telephone-transmitter, the combination of a casing composed ofseparable parts, electrodes in the casing,a diaphragm arranged inoperative relation to the electrodes, damping-springs bearing againstthe diaphragm, and fastening devices having inner enlarged extremitiesengaging the said dampingsprings and the opposite extremities projectingthrough a portion of the casing and exteriorly accessible, saidfastening devices being pivotally mounted within the casing.

5. In a telephone-transmitter, the combination of a casing composed ofseparable parts, electrodes disposed in the casing, adiaphragm in thecasing in operative relation to the electrodes, damping-springs appliedto the inner side of the diaphragm and having rearwardlyprojectingportions, and fastening devices pivotally disposed in the casing andhaving cam enlargements to engage the dampingsprings and screw-threadedshanks which extend through the casing to receive nuts, the projectingportions of the damping-springs engaging parts of the fastenings.

In testimony whereof I affix my signature in presence of two witnesses.

MILTON J. FLETCHER.

Witnesses:

THOMAS FARNswoRTH, NELsoN GOROM.

